About Offline Multiple Instances in Unity

When creating a world, I usually use “Build & Test your world” in Unity and check it with Clients2 to test global synchronization.

Since yesterday, when I try to run multiple instances like this, I get an error message.

The error says:
“You cannot join an online world while in offline test mode.”

Is there any solution to this?

Resolved:
Cleared the cache
&
The client was using a beta version.